Copper replaced aluminum nearly two decades ago as interconnect material in integrated circuit manufacturing, because of its better electrical conductivity. The size of the interconnect wire has been steadily decreasing as Moore's law has affected successive feature size generations. The diameter of the interconnect structure is expected to decrease further as silicon technology passes through additional generations. Alternatives to copper have been reported, notably, materials such as carbon nanotubes. The success has been limited, and carbon nanotubes have not yet been integrated into manufacturing practice. Most reports focused on providing vertical interconnects (vias) with multiwalled carbon nanotubes or carbon nanofibers for DRAM applications. Further, it is difficult to utilize carbon nanotubes for horizontally oriented local and global interconnects. It appears that standard copper will remain the preferred interconnect material for some time to come, if efficient methods to produce small diameter copper wires can be found.
What is needed is a method for reliably fabricating Cu nanowires with diameters as small as about 20 nm. Preferably, the method should rely, at least in part, upon techniques that are understood by workers in nanowire construction.